Endogenous Modulation of Cochlear Injury

描述(申请人提供)：顺铂是一种有效的化疗药物，广泛用于治疗恶性肿瘤。副作用，如耳毒性，损害了癌症幸存者的生活质量。顺铂可增加耳蜗内活性氧物种(ROS)的形成。NADPH氧化酶的一种独特的亚型NOX-3存在于大鼠耳蜗组织中。这种酶会产生超氧阴离子自由基，破坏外毛细胞，导致听力丧失。ROS可以激活可能具有保护作用或有害作用的耳蜗基因。保护性分子可能包括一种新的蛋白质，肾脏损伤分子(Kim)-1。顺铂在肾脏中诱导产生。该分子可促进近端小管细胞的修复和再生。本实验室首次发现了Kim-1在耳蜗处的表达以及顺铂对其的诱导作用。ROS可能会上调Kim-1的表达。目前尚不清楚这种蛋白质是否能保护耳蜗免受顺铂的影响。顺铂引起的ROS也可能增加潜在有害的瞬时受体潜在香草酸受体1(TRPV1)的表达。NOX-3和TRPV1的激活可能会压倒耳蜗组织的抗氧化防御，导致细胞死亡。在这一应用中的实验试图更准确地定义顺铂的耳毒性机制，以便找到将毒性降至最低的方法。建议的研究将利用耳蜗细胞系(UB/OC-1)和大鼠平行研究来解决三个特定目标：1)研究顺铂在耳蜗中激活NOX-3的机制；2)确定Kim-1的表达是否对顺铂耳毒性具有保护作用，并确定其诱导的潜在机制；以及3)研究TRPV1是否参与顺铂的耳毒性并确定其诱导机制。对于目标1，我们将系统地在圆形窗口(RW)上应用抗氧化剂硫辛酸或短干扰RNA(SiRNAs)来阻断顺铂对NOX-3的激活。在目标2中，我们将使用RW应用信号分子抑制剂来确定它们是否参与了Kim-1的诱导；以及RW应用对Kim-1的siRNA来查看顺铂是否增加了耳毒性。对于目标3，我们将研究RW应用TRPV1拮抗剂卡萨西平是否对顺铂耳毒性有保护作用。我们还将检查RW给予针对TRPV1的siRNA的效果，以确定这是否可以防止顺铂的耳毒性。本研究为顺铂耳毒性机制的研究提供了新的思路，并为缓解顺铂耳毒性提供了新的治疗方法。顺铂导致很大比例的癌症患者听力损失，这些患者接受这种药物来治愈他们的癌症。如果能发现一种在不干扰顺铂的癌症杀伤作用的情况下防止听力损失的治疗方法，将对癌症幸存者大有裨益。这项研究试图发现新的潜在治疗方法，以减少药物顺铂治疗癌症引起的听力损失的副作用。顺铂导致很大比例的癌症患者听力损失，这些患者接受这种药物来治愈他们的癌症。

DESCRIPTION (provided by applicant): Cisplatin is a potent chemotherapeutic agent widely used to treat malignant neoplasms. Side effects, like ototoxicity compromise the quality of life of cancer survivors. Cisplatin increases formation of reactive oxygen species (ROS) in the cochlea. A unique isoform of NADPH oxidase, NOX-3, is present in rat cochlea. This enzyme generates superoxide radicals that can damage outer hair cells (OHCs), leading to hearing loss. ROS can activate cochlear genes that may be protective or harmful. Protective molecules may include a novel protein, kidney injury molecule (KIM)-1. It is induced in kidney by cisplatin. This molecule may enhance repair and regeneration of proximal tubule cells. Our laboratory was the first to show KIM-1 in the cochlea and its induction by cisplatin. ROS may up-regulate KIM-1. It is unknown whether this protein protects the cochlea from cisplatin. ROS resulting from cisplatin may also increase expression of potentially harmful transient receptor potential vanilloid 1 receptors (TRPV1). Activation of NOX-3 and TRPV1 may overwhelm cochlear antioxidant defenses, leading to cell death. Experiments in this application seek to more precisely define mechanisms of cisplatin ototoxicity in order to find ways to minimize toxicity. Studies proposed will utilize a cochlear cell line (UB/OC-1) and parallel studies in rats to address three specific aims to: 1) investigate mechanisms of NOX-3 activation by cisplatin in the cochlea; 2) determine whether expression of KIM-1 confers protection against cisplatin ototoxicity and to determine potential mechanisms of its induction; and 3) study whether TRPV1 contributes to cisplatin ototoxicity and to determine mechanisms of its induction. For aim 1, we will administer systemically the antioxidant lipoic acid or short-interfering RNAs (siRNAs) on the round window (RW) to block activation of NOX-3 by cisplatin. In aim 2, we will use RW application of inhibitors of signaling molecules to see if they are involved in KIM-1 induction; and RW application of siRNA for KIM-1 to see if cisplatin ototoxicity increases. For aim 3, we will investigate whether RW application of the TRPV1 antagonist, capsazepine, protects against cisplatin ototoxicity. We will also examine effects of RW administration of siRNA against TRPV1 to see whether this prevents cisplatin ototoxicity. This research could provide new insights into mechanisms of cisplatin ototoxicity and novel therapeutic approaches to ameliorate cisplatin ototoxicity. Cisplatin causes hearing loss in a large percentage of cancer patients who receive this drug to cure their cancer. It would be of great benefit to cancer survivors if a treatment could be discovered that would prevent hearing loss without interfering with the cancer killing effects of cisplatin. This research seeks to discover new potential treatments to reduce the side effect of hearing loss resulting from the treatment of cancer with the drug cisplatin. Cisplatin causes hearing loss in a large percentage of cancer patients who receive this drug to cure their cancer.